Electric drive axle with multi-speed gearbox

ABSTRACT

An electric drive axle including a first shaft in driving engagement with an electric motor. A first gear and a second gear are coupled with the first shaft. A second shaft is disposed offset from the first shaft. A third gear is selectively coupled with the second shaft, and the third gear is meshed with the first gear. A fourth gear is selectively coupled with the second shaft, and the fourth gear is meshed with the second gear. A fifth gear is coupled with the second shaft and meshed with a sixth gear coupled with a differential case.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. National Phaseapplication Ser. No. 16/966,858, entitled “ELECTRIC DRIVE AXLE WITHMULTI-SPEED GEARBOX” and filed Jul. 31, 2020 U.S. application Ser. No.16/966,858 is a National Phase of International ApplicationPCT/US2018/028918, entitled “ELECTRIC DRIVE AXLE WITH MULTI-SPEEDGEARBOX,” filed on Apr. 23, 2018. International Patent ApplicationSerial No. PCT/US2018/028918 claims priority to U.S. ProvisionalApplication No. 62/625,920, filed on Feb. 2, 2018. The entire contentsof each of the above-mentioned applications are hereby incorporated byreference in their entirety for all purposes.

BACKGROUND

The present disclosure relates to gearboxes and electric drive axles.Electric and hybrid-electric vehicles utilize an electric power sourcein communication with an electric motor to provide drive, or augmenteddrive, to the vehicle. Electric vehicles have several characteristicssuperior to conventional internal combustion engine driven vehicles. Forexample, electric motors produce fewer vibrations than internalcombustion engines, and electric motors achieve maximum torque morequickly than internal combustion engines.

However, in order for the conventional electric vehicle to achievesufficient speed, the electric motor must allow for reasonable powerover a broad speed range. An electric motor which can provide reasonablepower over a broad speed range is typically large and heavy.

In view of the above, there remains a need for an electric drive axlehaving reduced size, weight, and production costs.

SUMMARY

The present disclosure provides for an electric drive axle. In oneembodiment, an electric drive axle includes a first shaft in drivingengagement with an electric motor. A first gear and a second gear arecoupled with the first shaft. A second shaft is disposed offset from thefirst shaft. A third gear is selectively coupled with the second shaft,and the third gear is meshed with the first gear. A fourth gear isselectively coupled with the second shaft, and the fourth gear is meshedwith the second gear. A fifth gear is coupled with the second shaft andmeshed with a sixth gear coupled with a differential case. The electricdrive axles further includes a first clutch disposed at least partiallyconcentrically within said second gear or said third gear and a firstfluid conduit disposed at least partially through the first shaft or thesecond shaft and in fluid communication with a clutch drum in the firstclutch.

In another embodiment, an electric drive axle includes an electric motorand a first shaft in driving engagement with the electric motor. A firstgear is coupled with the first shaft, and a second gear is selectivelycoupled with the first shaft. A second shaft is disposed offset from thefirst shaft. A third gear selectively coupled with the second shaft,wherein the third gear is meshed with the first gear. A fourth gear iscoupled with the second shaft, wherein the fourth gear is meshed withthe second gear. A fifth gear is coupled with said second shaft andmeshed with a sixth gear coupled with a differential case. The electricdrive axle further includes a first clutch disposed at least partiallyconcentrically within said second gear.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings are incorporated herein as part of thespecification. The drawings described herein illustrate embodiments ofthe presently disclosed subject matter, and are illustrative of selectedprinciples and teachings of the present disclosure. However, thedrawings do not illustrate all possible implementations of the presentlydisclosed subject matter, and are not intended to limit the scope of thepresent disclosure in any way.

FIG. 1 illustrates a schematic diagram of a vehicle driveline accordingto an embodiment of the presently disclosed subject matter;

FIG. 2 illustrates a portion of an electric drive axle of the drivelineaccording to FIG. 1;

FIG. 3 illustrates a portion of an electric drive axle according to FIG.2;

FIG. 4 illustrates a portion of an electric drive axle of the drivelineaccording to FIG. 1;

FIG. 5 illustrates a portion of an electric drive axle of the drivelineaccording to FIG. 1;

FIG. 6 illustrates a portion of an electric drive axle of the drivelineaccording to FIG. 1;

FIG. 7 illustrates a portion of an electric drive axle of the drivelineaccording to FIG. 1 with a housing removed;

FIG. 8 illustrates a cross-sectional view of the electric drive axleaccording to FIG. 6 along line A-A;

FIG. 9 illustrates a cross-sectional view of the electric drive axleaccording to FIG. 6 along line B-B;

FIG. 10 illustrates a portion of the electric drive axle according toFIG. 8;

FIG. 11 illustrates another portion of the electric drive axle accordingto FIG. 8;

FIG. 12 illustrates still another portion of the electric drive axleaccording to FIG. 8;

FIG. 13 illustrates yet another portion of the electric drive axleaccording to FIG. 8;

FIG. 14 illustrates a schematic diagram of an electric axle according toan embodiment of the presently disclosed subject matter; and

FIG. 15 illustrates a schematic diagram of an electric axle according toanother embodiment of the presently disclosed subject matter.

DETAILED DESCRIPTION

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific assemblies andsystems illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined herein. Hence, specific dimensions,directions or other physical characteristics relating to the embodimentsdisclosed are not to be considered as limiting, unless expressly statedotherwise. Also, although they may not be, like elements in variousembodiments described herein may be commonly referred to with likereference numerals within this section of the application.

Embodiments of an electric drive axle 100 are described below. Incertain embodiments, the electric drive axle 100 is utilized with a pureelectric vehicle (not depicted) where the electric drive axle 100 is theonly driving axle. In other embodiments, as illustrated in FIG. 1, theelectric drive axle is utilized with a hybrid all-wheel-drive vehicle10, where the front axle is driven by an internal combustion engine 12,and the rear axle is the electric drive axle 100. In still otherembodiments, the electric drive axle 100 is utilized in a hybridcommercial vehicle (not depicted) comprising a tandem axle in which thefront tandem axle is driven by an internal combustion engine, and therear tandem axle is the electric drive axle 100 (or vice versa). Theelectric drive axle 100 may have applications in commercial vehicles,both light duty and heavy-duty vehicles, and for passenger, off-highway,and sport utility vehicles. Additionally, the electric drive axle 100described herein may be adapted for use in front and/or rear drivingaxles, and in steerable and non-steerable axles. It would be understoodby one of ordinary skill in the art that the electric drive axle 100also has industrial, locomotive, military, agricultural, and aerospaceapplications.

As illustrated in FIGS. 2 and 3, in an embodiment, the electric driveaxle 100 may comprise an integrated drive system. In an embodiment, theelectric drive axle 100 includes an electric motor 104 coupled with apower source (not depicted). The electric motor 104 may be a permanentmagnet synchronous machine comprising a stator (not depicted) disposedconcentrically about a rotor (not depicted). The electric drive axle 100may additionally comprise an inverter (not depicted) for convertingdirect current to alternating current when the electric motor 104 isutilized to drive the vehicle, and for converting alternating current todirect current when the vehicle 10 decelerates. The electric motor 104may be referred to herein as a motor-generator. Further, the electricdrive axle 100 may include cooling fluid (not depicted) such as, but notlimited to, automatic transmission fluid or axle oil integrated with theelectric drive axle 100 lubricant for cooling the electric motor 104 andthe inverter. In another embodiment (not depicted), the cooling fluidfor the electric motor 104 and the inverter may not be integrated withthe axle oil.

A motor output shaft 106 is coupled with the rotor of the electric motor104 for rotation therewith. A first gear 108 and a second gear 110 arecoupled with the motor output shaft 106 for rotation therewith. In anembodiment, the first and second gears 108, 110 are forged on the motoroutput shaft 106. In another embodiment, the first and second gears 108,110 may be welded to the motor output shaft 106. In still anotherembodiment, the first and second gears 108, 110 may be splined to themotor output shaft 106. The electric motor 104 drives a compound idlerassembly 112 via the motor output shaft 106 and the first and secondgears 108, 110. In an embodiment, the motor output shaft 106, thecompound idler assembly 112, and axle shafts 16, 18 are disposed offsetand parallel relative to one another.

As illustrated in FIGS. 4-8, the compound idler assembly 112 comprisesan idler shaft 114 rotatably supported in an axle housing 102 via firstand second bearings 116A, 116B. The idler shaft 114 comprises a firstportion 118, a second portion 120, a third portion 122A, and a fourthportion 122B. The first and second portions 118, 120 may be disposed atopposing ends of the idler shaft 114 and have the same diameter. Theidler shaft third and fourth portions 122A, 122B may be disposed axiallybetween the first and second portions 118, 120, and the diameter of thefirst and second portions 118, 120 may be smaller than a diameter of thethird and fourth portions 122A, 122B. The first bearing 116A is disposedconcentrically about the idler shaft first portion 118, and the secondbearing 116B is disposed concentrically about the idler shaft secondportion 120. In an embodiment, the idler shaft third and fourth portions122A, 122B may be splined.

A third gear 124 is disposed concentrically about at least a portion ofthe idler shaft third portion 122A. The third gear 124 is in meshedengagement with the first gear 108 and receives torque therefrom whenthe electric motor 104 outputs torque to the motor output shaft 106. Thethird gear 124 comprises the general geometry of a hollow right circularcylinder. The third gear 124 is part of a first clutch assembly 125. Asillustrated in FIG. 8, in an embodiment, the first clutch assembly 125comprises a first clutch drum 126 disposed at least partiallyconcentrically within the third gear 124. A radially outer surface ofthe first clutch drum 126 is coupled with a radially inner surface ofthe third gear 124. In an embodiment, the first clutch drum 126 and thethird gear 124 may be coupled via splined engagement. In anotherembodiment, the first clutch drum 126 and the third gear 124 may becoupled via an interference fit. In yet another embodiment (notdepicted), the third gear 124 and the clutch drum 126 may comprise aunitary component.

A first clutch hub 128 is disposed at least partially concentricallywithin the first clutch drum 126. The first clutch hub 128 may comprisea splined radially inner surface in meshed engagement with complimentarysplines on the idler shaft third portion 122A. A first axially outersurface 130 of the first clutch hub 128 abuts the first bearing 116A.The third gear 124 is entirely supported on the idler shaft 114 by thefirst clutch hub 128 via the first clutch drum 126.

The first clutch drum 126 comprises a plurality of radially inwardextending splines 132 defined on a radially inner surface thereof. Thefirst clutch drum splines 132 may extend the axial length of theradially inner surface of the first clutch drum 126. A first pluralityof clutch plates 134 are in meshed engagement with the first clutch drumsplines 132. The clutch plates 134 receive torque from the first clutchdrum 126 and may move axially within the first clutch drum 126.

The first clutch hub 128 comprises a first portion 136, a second portion138, and a third portion 140. The first portion 136 defines a pluralityof axially extending splines 142. The second and third portions 138, 140are disposed on either axial side of the first portion 136,respectively. A second plurality of clutch plates 144 are in meshedengagement with the first clutch hub splines 142. The second pluralityof clutch plates 144 are interleaved with the first plurality of clutchplates 134. The second plurality of clutch plates 144 may move axiallyalong the first clutch hub splines 142.

In an embodiment, a first needle bearing 146 is disposed about andcoupled with the first clutch hub third surface 240. The first needlebearing 146 provides rotational support of the first clutch drum 126. Asecond needle bearing 148 is disposed about and coupled with the firstclutch hub second surface 138. As illustrated in FIGS. 8 and 10, a firstsupport plate 150 is disposed about and rotationally supported by thesecond needle bearing 148. In an embodiment, the first support plate 150comprises a radially outer surface having a plurality of radiallyprojecting splines 152. The splines 152 may also be a plurality of teethor lugs. The splines 152 mesh with the first clutch drum splines 132.The first support plate 150 further comprises a plurality of axiallyextending apertures 154 therethrough.

As illustrated in FIGS. 8 and 11, a first pressure plate 156 may bedisposed axially between the support plate 150 and the plurality ofclutch plates 134, 144. The first pressure plate 156 is disposedconcentric with the first clutch hub 128. The first pressure plate 156comprises a plurality of radially extending teeth 158. The teeth 158 mayalso be referred to herein as splines or lugs. The first pressure plateteeth 158 are meshed with the first clutch drum splines 132.

A first apply plate 160 may be disposed at least partially about thefirst clutch hub 128. As illustrated in FIGS. 8 and 12, in anembodiment, the first apply plate 160 may comprise a plurality ofaxially projecting lugs 162. The lugs 162 may be disposed through thefirst support plate apertures 154. The lugs 162 abut a surface of thefirst pressure plate 156 and apply an axial force thereto duringengagement of the plurality of clutch plates 134, 144. The first applyplate also comprises an axially extending flange 164. In an embodiment,the axially extending flange 164 may share a radially inner surface witha surface of the first apply plate 160 having the smallest diameter ofthe first apply plate 160. The first apply plate 160 may further includea radially extending flange 166. A first biasing member 168 may bedisposed axially between the first apply plate radially extending flange166 and the first support plate 150.

As illustrated in FIGS. 8 and 13, a first piston member 170 may bedisposed at least partially concentrically about said idler shaft 114.The piston member 170 may also be disposed axially adjacent to the firstapply plate 160. The first piston member 170 comprises an axiallyextending flange 172. The axially extending flange 172 protrudes towardsthe first apply plate 160 when assembled. A first thrust bearing 174 isdisposed axially between the first piston member 170 and the first applyplate 160. The first thrust bearing 174 is also disposed at leastpartially radially between the first piston member axially extendingflange 172 and the first apply plate axially extending flange 164.

As illustrated in FIG. 8, a first bushing 176 may be disposed about thefirst clutch hub second portion 138 adjacent to an end of the secondneedle bearing 148 that is distal from the first clutch hub firstportion 136. The first bushing 176 is also disposed radially within thefirst apply plate 160. A first shim 178 may be disposed about the firstclutch hub second portion 138 adjacent to the first bushing 176. Thefirst shim 178 is also disposed radially within the first apply plate160. A first snap ring 180 may be disposed at least partially in agroove defined by the first clutch hub second portion 128. The firstsnap ring 180 is disposed axially adjacent to the first shim 178, and isalso disposed radially within the first apply plate 160. Additionally, asecond thrust bearing 182 is disposed adjacent to an axially outersurface of the first clutch drum 126 distal from the first apply plate160.

A fourth gear 184 is disposed concentrically about the idler shaft thirdportion 122B. The fourth gear 184 is in meshed engagement with thesecond gear 110 and receives torque therefrom when the electric motor104 outputs torque to the motor output shaft 106. The fourth gear 184comprises the general geometry of a hollow right circular cylinder. Thefourth gear 184 is part of a second clutch assembly 225. As illustratedin FIG. 8, in an embodiment, the second clutch assembly 225 comprises asecond clutch drum 226 disposed at least partially concentrically withinthe fourth gear 184. A radially outer surface of the second clutch drum226 is coupled with a radially inner surface of the fourth gear 184. Inan embodiment, the second clutch drum 226 and the fourth gear 184 may becoupled via splined engagement. In another embodiment, the second clutchdrum 226 and the fourth gear 184 may be coupled via an interference fit.In yet another embodiment (not depicted), the fourth gear 184 and thesecond clutch drum 226 may comprise a unitary component.

A second clutch hub 228 is disposed concentrically, and at leastpartially axially, within the second clutch drum 226. The second clutchhub 228 comprises a splined radially inner surface in meshed engagementwith complimentary splines on the idler shaft third portion 122A. Afirst surface 230 of the second clutch hub 228 abuts the first bearing116A. The fourth gear 184 is entirely supported on the idler shaft 114by the second clutch hub 228 via the second clutch drum 226.

The second clutch drum 226 comprises a plurality of radially extendingsplines 232 defined on a radially inner surface thereof. The splines 232may extend the axial length of the radially inner surface of the secondclutch drum 226. A first plurality of clutch plates 234 are in meshedengagement with the second clutch drum splines 232. The clutch plates234 receive torque from the second clutch drum 226 and may move axiallywithin the second clutch drum 226.

The second clutch hub 228 may comprise a first portion 236, a secondportion 238, and a third portion 240. The first portion 236 defines aplurality of axially extending splines 242. The second and thirdportions 238, 240 are disposed on either axial side of the first portion236, respectively. A second plurality of clutch plates 244 are in meshedengagement with the second clutch hub splines 242. The second pluralityof clutch plates 244 are interleaved with the first plurality of clutchplates 234. The second plurality of clutch plates 244 may move axiallyalong the second clutch hub splines 242.

A third needle bearing 246 is disposed about and coupled with the secondclutch hub third surface 240. The third needle bearing 246 providesrotational support of the second clutch drum 226. A fourth needlebearing 248 is disposed about and coupled with the second clutch hubsecond surface 238. As illustrated in FIGS. 8 and 10, a second supportplate 250 is disposed about and rotationally supported by the fourthneedle bearing 248. The second support plate 250 comprises a radiallyouter surface having a plurality of radially projecting splines 252. Thesplines 252 may also be a plurality of teeth or lugs. The splines 252mesh with the second clutch drum splines 232. The second support plate250 further comprises a plurality of axially extending apertures 254therethrough.

A second pressure plate 256 is disposed axially between the secondsupport plate 250 and the plurality of clutch plates 234, 244. Thesecond pressure plate 256 is disposed concentric with the second clutchhub 228. The second pressure plate 256 comprises a plurality of radiallyextending teeth 258. The teeth 258 may also be referred to herein assplines or lugs. The second pressure plate teeth 258 are meshed with thesecond clutch drum splines 232.

A second apply plate 260 is disposed at least partially about the secondclutch hub 228. As illustrated in FIGS. 8 and 12, in an embodiment, thesecond apply plate 260 may comprise a plurality of axially projectinglugs 262. The lugs 262 may be disposed through second support plateapertures 254. The lugs 262 abut a surface of the second pressure plate256 and apply an axial force thereto during engagement of the pluralityof clutch plates 234, 244. The second apply plate 260 also comprises anaxially extending flange 264. In an embodiment, the axially extendingflange 264 may comprise a radially inner surface having a diameter equalto that of a radially inner surface 265 of the second apply plate 260.The second apply plate 260 may further include a radially extendingflange 266. A second biasing member 268 may be disposed axially betweenthe first apply plate radially extending flange 266 and the secondsupport plate 250.

As illustrated in FIGS. 8 and 13, a second piston member 270 is disposedat least partially concentrically about the idler shaft 114. The secondpiston member 270 is also disposed axially adjacent to the second applyplate 260. The second piston member 270 comprises an axially extendingflange 272. The axially extending flange 272 protrudes towards thesecond apply plate 260 when assembled. A third thrust bearing 274 isdisposed axially between the second piston member 270 and the secondapply plate 260. The third thrust bearing 274 is also disposed at leastpartially radially between the second piston member axially extendingflange 272 and the second apply plate axially extending flange 264.

As illustrated in FIG. 8, a second bushing 276 may be disposed about thesecond clutch hub second portion 238 adjacent to an end of the fourthneedle bearing 248 distal from the second clutch hub first portion 236.The second bushing 276 is also disposed radially within said secondapply plate 260. A second shim 278 may be disposed about the secondclutch hub second portion 238 adjacent to the second bushing 276. Thesecond shim 278 is also disposed radially within the second apply plate260. A second snap ring 280 is disposed at least partially in a groovedefined by the second clutch hub second portion 228. The second snapring 280 is disposed axially adjacent to the second shim 278, and isalso disposed radially within the second apply plate 260. Additionally,a fourth thrust bearing 282 is disposed adjacent to an axially outersurface of the second clutch drum 226 distal from the second apply plate260.

When the first clutch assembly 125 is engaged, the third gear 124receives torque from the first gear 108 and outputs torque to the idlershaft 114. When the second clutch assembly 225 is engaged, the fourthgear 184 receives torque from the second gear 110 and outputs torque tothe idler shaft 114. Only one of the first and second clutch assemblies125, 225 is engaged at one time during vehicle operation. However, in aparking brake mode, both the first and second clutch assemblies 125, 225may be engaged simultaneously. The first and second clutch assemblies,125, 225 also act as support members of the gear train.

As illustrated in FIGS. 2-7, the electric drive axle 100 may comprise ahydraulic actuator assembly 300. The hydraulic actuator 300 is in fluidcommunication with portions 302, 304 of the axle housing 102 (see FIG.9). The hydraulic actuator 300 utilizes pressurized fluid to actuate thefirst and second piston members 170, 270 and thereby engage the firstand second clutch assemblies 125, 225, respectively.

As illustrated in FIG. 8, a fifth gear 186 is coupled with the idlershaft 114. In an embodiment, as illustrated in FIG. 8, the fifth gear186 may be forged on the idler shaft 114. The fifth gear 186 is inmeshed engagement with a sixth gear 188. As illustrated in FIG. 7, thesixth gear 188 is coupled with, and fixed for rotation with, adifferential case 402. The differential case 402 is part of adifferential mechanism 400. The differential case 402 is rotatablysupported within the axle housing 102 via a pair of bearings 404, 406.The differential mechanism 400 further includes two or more differentialpinions 408. The differential pinions 408 are coupled within thedifferential case 402 via a pinion shaft 410 (i.e., spider shaft). In anembodiment, the pinion shaft 410 may comprise a cross member. Thedifferential pinions 408 are in meshed engagement with a first side gear412 and a second side gear (not depicted). The first side gear 412 iscoupled for rotation with the first axle shaft 16, and the second sidegear is coupled for rotation with the second axle shaft 18.

In another embodiment, as illustrated in FIG. 14, an electric drive axle500 may comprise an electric motor 504 coupled with a power source (notdepicted). The electric motor 504 may be a permanent magnet synchronousmachine comprising a stator (not depicted) disposed concentrically abouta rotor (not depicted). A motor output shaft first portion 506A andsecond portion 506B are rotatably disposed within a housing (notdepicted) via a first bearing 505A and a second bearing 505B. The motoroutput shaft first portion 506A is coupled with the rotor of theelectric motor 504 for rotation therewith. A first gear 508 is coupledwith the motor output shaft first portion 506A for rotation therewith.In an embodiment, the first gear 508 is forged on the motor output shaftfirst portion 506A. In other embodiments, the first gears 508 may bewelded, splined, or press-fit to the motor output shaft first portion506A. The electric motor 504 selectively drives a compound idlerassembly 512 via the motor output shaft first portion 506A and the firstgear 508. In an embodiment, the motor output shaft first portion 506A,the compound idler assembly 512, and axle shafts 16, 18 are disposedoffset and parallel relative to one another.

The compound idler assembly 512 comprises an idler shaft 514 rotatablysupported in an axle housing (not depicted) via first and secondbearings 516A, 516B. A third gear 524 is disposed concentrically aboutat least a portion of the idler shaft 514. The third gear 524 is inmeshed engagement with the first gear 508 and receives torque therefromwhen the electric motor 504 outputs torque to the motor output shaft506. In an embodiment, the third gear 524 comprises the general geometryof a hollow right circular cylinder. The third gear 524 is part of afirst clutch assembly 525. In an embodiment, the first clutch assembly525 comprises a first clutch drum 526 disposed at least partiallyconcentrically within the third gear 524. A radially outer surface ofthe first clutch drum 526 is coupled with a radially inner surface ofthe third gear 524. In an embodiment, the first clutch drum 526 and thethird gear 524 may be coupled via splined engagement. In anotherembodiment, the first clutch drum 526 and the third gear 524 may becoupled via an interference fit. In yet another embodiment, the thirdgear 524 and the clutch drum 526 may comprise a unitary component.

A first clutch hub 528 is disposed at least partially concentricallywithin the first clutch drum 526. The first clutch hub 528 is coupledfor rotation with the idler shaft 514. In an embodiment, the firstclutch hub 528 may comprise a splined radially inner surface in meshedengagement with complimentary splines on the idler shaft 514. The thirdgear 524 is entirely supported on the idler shaft 514 by the firstclutch hub 528 via the first clutch drum 526.

A first plurality of clutch plates 534 are coupled for rotation with thefirst clutch drum 526. The clutch plates 534 receive torque from thefirst clutch drum 526 and may move axially within the first clutch drum526. A second plurality of clutch plates 544 are in meshed engagementwith the first clutch hub 528. The second plurality of clutch plates 544are interleaved with the first plurality of clutch plates 534. Thesecond plurality of clutch plates 544 may move axially along the firstclutch hub 528.

A fourth gear 584 is coupled for rotation with the idler shaft 514. Thefourth gear 584 is in meshed engagement with a second gear 510 andselectively receives torque therefrom. The second gear 510 may bedisposed about the motor output shaft second portion 506B. A secondclutch 625 is disposed about the motor output shaft second portion 506Band coupled with the second gear 510. In an embodiment, the second gear510 may be coupled with a second clutch drum 626 disposed about themotor output shaft second portion 506B. The second clutch drum 626 issupported on the motor output shaft second portion 506B via a bearing627 for selective rotation relative to the motor output shaft first andseconds portions 506A, 506B. The motor output shaft first and secondportions 506A, 506B are unitary and integral.

In an embodiment, a second clutch hub 628 is disposed at least partiallyconcentrically within the second clutch drum 626. The second clutch hub628 is coupled for rotation with the motor output shaft second portion506B. In an embodiment, the second clutch hub 628 may comprise a splinedradially inner surface in meshed engagement with complimentary splineson the motor output shaft second portion 506B. In another embodiment,the second clutch hub 628 may be formed unitary and integral with themotor output shaft second portion 506B.

A first plurality of clutch plates 634 are coupled for rotation with thesecond clutch drum 626. The clutch plates 634 receive torque from thesecond clutch drum 626 and may move axially within the second clutchdrum 626. In an embodiment, a second plurality of clutch plates 644 arein meshed engagement with the second clutch hub 628. In anotherembodiment, the second plurality of clutch plates 644 may be in meshedengagement directly with the motor output shaft second portion 506B. Thesecond plurality of clutch plates 644 are interleaved with the firstplurality of clutch plates 634. The second plurality of clutch plates644 may move axially along the second clutch hub 628.

In an embodiment, the motor output shaft second portion 506B comprises afluid conduit 646 disposed at least partially axially therethrough.Apertures in the motor output shaft second portion 506B facilitate fluidcommunication between the fluid conduit 646 and the second clutch 625. Ahydraulic actuator (not depicted) may be in fluid communication with thefluid conduit 646. The hydraulic actuator utilizes pressurized fluid toactuate a piston member 670 disposed within the second clutch drum 626.The piston member 670 is sealed within the second clutch drum 626, andthe hydraulic actuator thereby applies an axial load to the first andsecond pluralities of clutch plates 634, 644 to transfer torque from themotor output shaft first portion and second portion 506A, 506B to thesecond clutch drum 626 and the second gear 510. A biasing member (notdepicted) is also disposed within the second clutch drum 626, anddecompresses to actuate the piston member 670 and evacuate thepressurized fluid from the second clutch drum 626 when the second clutch625 is disengaged. A clutch drum cover portion 671 may be coupled withthe motor output shaft first portion 506A. The cover portion 671 may besealing coupled with a radially inner surface of the second clutch drum626 and rotate relative to the second clutch drum 626 when the secondclutch 625 is disengaged. In an embodiment, the first clutch 525 maycomprise substantially the same components described with regard to thefirst clutch 125, and may be selectively engaged/disengaged via thehydraulic actuator.

A fifth gear 586 is coupled with the idler shaft 514. In an embodiment,the fifth gear 586 may be forged on the idler shaft 514. The fifth gear586 is in meshed engagement with the differential mechanism 400described supra via the sixth gear 188.

In another embodiment, as illustrated in FIG. 15, an electric drive axle700 may comprise an electric motor 704 coupled with a power source (notdepicted). The electric motor 704 may be a permanent magnet synchronousmachine comprising a stator (not depicted) disposed concentrically abouta rotor (not depicted). A motor output shaft 706 is rotatably disposedwithin a housing (not depicted) via a first bearing 705A and a secondbearing 705B. The motor output shaft 706 is coupled with the rotor ofthe electric motor 704 for rotation therewith. A first gear 708 and asecond gear 710 may be coupled with the motor output shaft first 706 forrotation therewith. In an embodiment, the first and second gears 708,710 may be forged on the motor output shaft 706. In other embodiments,the first and second gears 708, 710 may be welded, splined, or press-fitto the motor output shaft 706. The electric motor 704 drives a compoundidler assembly 712 via the motor output shaft 706 and the first orsecond gear 708, 710. In an embodiment, the motor output shaft 706, thecompound idler assembly 712, and axle shafts 16, 18 are disposed offsetand parallel relative to one another.

The compound idler assembly 712 comprises an idler shaft 714 rotatablysupported in an axle housing (not depicted) via first and secondbearings 716A, 716B. A third gear 724 is disposed concentrically aboutat least a portion of the idler shaft 714. The third gear 724 is inmeshed engagement with the first gear 708 and receives torque therefromwhen the electric motor 704 outputs torque to the motor output shaft706. In an embodiment, the third gear 724 comprises the general geometryof a hollow right circular cylinder. The third gear 724 is part of afirst clutch assembly 725. In an embodiment, the first clutch assembly725 comprises a first clutch drum 726 disposed at least partiallyconcentrically within the third gear 724. A radially outer surface ofthe first clutch drum 726 is coupled with a radially inner surface ofthe third gear 724. In an embodiment, the first clutch drum 726 and thethird gear 724 may be coupled via splined engagement. In anotherembodiment, the first clutch drum 726 and the third gear 724 may becoupled via an interference fit. In yet another embodiment, the thirdgear 724 and the clutch drum 726 may comprise a unitary component. Thefirst clutch drum 726 may be rotatably supported on the intermediateshaft 714 via a pair of bearings 727.

A first clutch hub 728 may be disposed at least partially concentricallywithin the first clutch drum 726. The first clutch hub 728 is coupledfor rotation with the idler shaft 714. In an embodiment, the firstclutch hub 728 may comprise a splined radially inner surface in meshedengagement with complimentary splines on the idler shaft 714. The thirdgear 524 may be supported on the idler shaft 714 by the first clutch hub728 via the first clutch drum 726.

A first plurality of clutch plates 734 are coupled for rotation with thefirst clutch drum 726. The clutch plates 734 receive torque from thefirst clutch drum 726 and may move axially within the first clutch drum726. A second plurality of clutch plates 744 are in meshed engagementwith the first clutch hub 728. The second plurality of clutch plates 744are interleaved with the first plurality of clutch plates 734. Thesecond plurality of clutch plates 744 may move axially along the firstclutch hub 728. In an embodiment, the second plurality of clutch plates744 may be splined directly to the idler shaft 714. Additionally, apiston member 770 may be disposed within the first clutch drum 726. Thepiston member 770 and the clutch plates 734, 744 may be sealed withinthe first clutch drum 726 via seals 771 and a clutch drum cover 729.

A fourth gear 784 is at least partially disposed about the idler shaft714. The fourth gear 784 is in meshed engagement with a second gear 710and receives torque therefrom. The fourth gear 784 is part of a secondclutch assembly 825. In an embodiment, the second clutch assembly 825comprises a second clutch drum 826 disposed at least partiallyconcentrically within the third gear 824. A radially outer surface ofthe first clutch drum 826 is coupled with a radially inner surface ofthe third gear 824. In an embodiment, the first clutch drum 826 and thethird gear 824 may be coupled via splined engagement. In anotherembodiment, the first clutch drum 826 and the third gear 824 may becoupled via an interference fit. In yet another embodiment, the thirdgear 824 and the clutch drum 826 may comprise a unitary component. Thefirst clutch drum 826 may be rotatably supported on the intermediateshaft 814 via a pair of bearings 827.

A second clutch hub 828 may be disposed at least partiallyconcentrically within the first clutch drum 826. The second clutch hub828 is coupled for rotation with the idler shaft 714. In an embodiment,the second clutch hub 828 may comprise a splined radially inner surfacein meshed engagement with complimentary splines on the idler shaft 714.The fourth gear 784 may be supported on the idler shaft 714 by thesecond clutch hub 828 via the second clutch drum 826.

A first plurality of clutch plates 834 are coupled for rotation with thesecond clutch drum 826. The clutch plates 834 receive torque from thesecond clutch drum 826 and may move axially within the second clutchdrum 826. A second plurality of clutch plates 844 are in meshedengagement with the second clutch hub 828. The second plurality ofclutch plates 844 are interleaved with the first plurality of clutchplates 834. The second plurality of clutch plates 844 may move axiallyalong the second clutch hub 828. In an embodiment, the second pluralityof clutch plates 844 may be splined directly to the idler shaft 714.Additionally, a piston member 870 may be disposed within the secondclutch drum 826. The piston member 870 and the clutch plates 834, 844may be sealed within the second clutch drum 826 via seals 871 and aclutch drum cover 829.

In an embodiment, the idler shaft 714 may comprise first and secondfluid conduits 715A, 715B disposed in the ends thereof. The first andsecond fluid conduits 715A, 715B may be disposed coaxially with theidler shaft 714. Apertures 717A, 717B may be disposed radially throughthe idler shaft 714, placing the first and second fluid conduits 715A,715B in fluid communication with the interior of the first and secondclutches 725, 825, respectively.

A hydraulic actuator (not depicted) may be in fluid communication withthe first and second fluid conduits 715A, 715B. The hydraulic actuatorutilizes pressurized fluid to actuate selectively actuate the pistonmembers 770, 870. A biasing member (not depicted) is also disposedwithin each of the first and second clutch drums 726, 826. The biasingmember decompresses to actuate the piston members 770, 870 and evacuatethe pressurized fluid from the first and second clutch drums 726, 826when the first and second clutches 725, 825 are disengaged,respectively.

A fifth gear 786 is coupled with the idler shaft 714. In an embodiment,the fifth gear 786 may be forged on the idler shaft 714. The fifth gear786 may be disposed axially between the first and second clutches 725,825. The fifth gear 786 is in meshed engagement with the differentialmechanism 400, described supra, via the sixth gear 188.

During operation, either the first clutch 725 or the second clutch 825is engaged at one time to select a desired gear ratio, and transfertorque from the motor output shaft 706 to the idler shaft 714, and fromthe idler shaft 714 to the differential mechanism 400. However, both thefirst and second clutches 725, 825 may be engaged simultaneously to actas a parking brake.

One or more features of the embodiments described supra may be combinedto create additional embodiments which are not depicted. While variousembodiments have been described above, it should be understood that theyhave been presented by way of example, and not limitation. It will beapparent to persons skilled in the relevant arts that the disclosedsubject matter may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The embodimentsdescribed above are therefore to be considered in all respects asillustrative, not restrictive.

What is claimed is:
 1. An electric drive axle, comprising: an electricmotor-generator; a motor-generator output shaft; an idler shaft; a geartrain including: a first gear coupled directly to the motor-generatoroutput shaft; a second gear directly or selectively coupled to themotor-generator output shaft; a third gear selectively coupled to theidler shaft; a fourth gear directly or selectively coupled to the idlershaft; and a fifth gear coupled to the idler shaft and coupled to adifferential case; a first clutch assembly including a first clutch drumdisposed at least partially concentrically within the third gear; and asecond clutch assembly including a second clutch drum disposed at leastpartially concentrically within the second gear or the fourth gear. 2.The electric drive axle of claim 1, further comprising: a first fluidconduit disposed at least partially through the idler shaft and in fluidcommunication with a first piston member in the first clutch assembly;and a second fluid conduit disposed at least partially through the idlershaft and in fluid communication with a second piston member in thesecond clutch assembly.
 3. The electric drive axle of claim 1, whereinthe idler shaft is supported by a housing.
 4. The electric drive axle ofclaim 1, wherein the electric motor-generator is a permanent magnetsynchronous motor-generator.
 5. The electric drive axle of claim 1,further comprising a first needle bearing coupled to the first clutchdrum and a second needle bearing coupled to the second clutch drum. 6.The electric drive axle of claim 1, further comprising a first thrustbearing and a second thrust bearing coupled to opposing sides of theidler shaft.
 7. The electric drive axle of claim 1, wherein the firstclutch drum is in splined engagement with the third gear.
 8. Theelectric drive axle of claim 1, wherein the first clutch drum and thethird gear are interference fit.
 9. The electric drive axle of claim 1,wherein the first clutch drum and the third gear form a unitarycomponent.
 10. The electric drive axle of claim 1, wherein the first andsecond clutch assemblies are designed to be engaged simultaneously in aparking brake mode.
 11. An electric drive system, comprising: anelectric motor-generator; a motor-generator output shaft rotationallycoupled to the electric motor-generator; an idler shaft; a gear trainincluding a plurality of gears coupled to the motor-generator outputshaft and the idler shaft; a first clutch assembly including a firstclutch drum that is disposed at least partially concentrically within afirst gear on the idler shaft; a second clutch assembly including asecond clutch drum that is disposed at least partially concentricallywithin a second gear on the idler shaft; a first fluid conduit disposedat least partially through the idler shaft and in fluid communicationwith the first clutch assembly; and a second fluid conduit disposed atleast partially through the idler shaft and in fluid communication withthe second clutch assembly.
 12. The electric drive system of claim 11,wherein: the first fluid conduit is in fluidic communication with afirst piston member in the first clutch assembly; and the second fluidconduit is in fluidic communication with a second piston member in thesecond clutch assembly.
 13. The electric drive system of claim 11,wherein the first clutch drum is in splined engagement or interferencefit with the first gear.
 14. The electric drive system of claim 11,wherein the first fluid conduit and the second fluid conduit are inhydraulic communication with a hydraulic actuator assembly.
 15. Theelectric drive system of claim 11, further comprising: a first needlebearing coupled to the first clutch drum and a second needle bearingcoupled to the second clutch drum; and a first thrust bearing and asecond thrust bearing coupled to opposing sides of the idler shaft. 16.The electric drive system of claim 15, wherein the first and secondthrust bearings are positioned axially outboard of the first and secondneedle bearings with regard to the idler shaft.
 17. The electric drivesystem of claim 11, further comprising a third gear coupled to the idlershaft and a differential case and wherein the idler shaft and adifferential case are rotatably supported by a housing.
 18. The electricdrive system of claim 11, the first and second fluid conduits aredisposed on opposite sides of the idler shaft.
 19. The electric drivesystem of claim 11, wherein: the first clutch assembly includes aplurality of plates moving axially along the first clutch hub duringactuation; and the second clutch assembly includes a plurality of platesmoving axially along the second clutch hub during actuation.
 20. Theelectric drive system of claim 11, wherein: in a first mode, the firstand second clutch assemblies are designed to engage one at a time toselect a desired gear ratio; and in a second mode, the first and secondclutch assemblies are designed to simultaneously engage.